If you've used the iOS app, the Mac app won't be too much of a surprise. The same minimal interface tags along on the Mac version, and all your to-dos are synced up across devices. The app also features Notification Center integration for reminders, badges for reference to how many to-dos you have left, and a nice quick access button in the menu bar. You also get all the features of the iOS version, including the ability to easily share lists, attach video, audio, and photos, and more.